1. Field of the Invention
This invention relates to star couplers for the distribution of signals in optical communication systems.
2. Description of the Prior Art
A key component in many architectures of high-speed, optical signal distribution systems is a single-mode-fiber passive star coupler. Under ideal conditions, a transmissive star coupler having n inputs and n outputs, hereinafter referred to as an n.times.n star, divides the power entering any of its n input ports equally between its n output ports. Naturally, there is some loss of power within the star coupler due to absorption and scattering. The n.times.n star coupler can be used as the central node of a high speed, optical, local-area network where each user would be connected by two fibers--one for transmissions to the input side of the star, and the other for reception from the output side of the star. This arrangement creates a broadcast -type local-area network where a message which is transmitted by any user can be received by all users. In use, different messages can be transmitted and received simultaneously by the various users through the application of any of a number of protocols such as wavelength--division multiple access or time-division multiple access. A disadvantage of the transmissive star architecture is that a large amount of fiber and a relatively large number of components are required for implementation.